Groundwater and soil contamination has been associated with higher incidence of birth defects and cancer. Monitored natural attenuation of contaminants via biodegradation has proven effective in lowering contaminant levels, but these processes depend critically on dissolved oxygen levels. This project proposes to develop a robust oxygen sensor compound with chemical durability required for long-term in-situ subsurface monitoring. The proposed technology is aimed at reducing the costs associated with the installation of monitoring wells and repetitive groundwater sampling for dissolved oxygen. Furthermore, it delivers higher accuracy by sampling in-situ. These performance enhancements and cost reductions will facilitate the expansion and acceleration of current environmental remediation projects. In addition to environmental markets, the proposed technology would be applicable to other industries, such as in agriculture and chemical processing. Improvements in the physical chemistry of oxygen sensors will likely generalize to the development of rugged sensors for other environmentally significant parameters, such as pH, redox potential. ChromoSense LLC was founded to develop innovative optical sensing and monitoring solutions for the environmental monitoring market, and it has been conducting research on the development of a full range of low-cost optical sensor probes for long- term in-situ monitoring. In order to commercialize the proposed dissolved oxygen probe, the company and the partner university will draw upon its team's many combined years of professional experience in the proposed application and technological development. Keywords: Environmental Remediation, Subsurface Dissolved Oxygen Monitoring, Fiber Optic Sensor.